Megatack is an arcade game published by Taiyo System in 1980.
Each wave consists of two rounds. The first round pits you against descending "space monsters", while the second consists of "space rings" that grow in size if you don't shoot them first and try to absorb your ship. Completing both rounds takes you to the next wave.
Other machines made by Taiyo System during the time period Megatack was produced include Tora Tora, Intruder, Enigma II, Kaos, and Pot Of Gold.